The Byzantine Empire also known as the Eastern Roman Empire or simply Byzantium was the heir Roman Empire State who survived throughout the Middle Ages and early Renaissance and was located in the eastern Mediterranean. Its capital was in Constantinople whose oldest name was Byzantium. It is also known as the Byzantine Empire Eastern Roman Empire, especially to refer to the first centuries of existence, during late antiquity, when the Roman Empire was still going to exist.
Map of the Vandalic War
Flavius Belisarius was the most important general of the Eastern Roman Empire and right hand of the Emperor Justinian who decided to get back the Western Roman territories lost about a century before.
The enlargement of the Roman Empire possessions between the rise to power of Justinian (red, 527) and his and Belisarius' death (orange, 565). Belisarius contributed greatly to the expansion of the empire.
The term "Byzantine Empire" (Byzantine, old name of Constantinople) was a creation of the German historian Hieronymus Wolf, who in 1557-a century after the fall of Constantinople used it in his work Corpus Historiae Byzantinae to designate this period the story in contrast to the Greek and Roman cultures of classical antiquity. The term did not become common until the eighteenth century, when it was popularized by French authors such as Montesquieu.
Byzantine Emperor Justinian I attempted to reconquer the fallen half of the Roman empire, but much of his reconquered land was lost following his death.